Backward Diffusion Methods for Digital Halftoning

Abstract

We examine using discrete backward diffusion to produce digital halftones.
The noise introduced by the discrete approximation to backwards diffusion forces
the intensity away from uniform values, so that rounding each pixel to black or
white can produce a pleasing halftone. We formulate our method by considering
the Human Visual System norm and approximating the inverse of the blurring
operator. We also investigate several possible mobility functions for use in a
nonlinear backward diffusion equation for higher quality results.